Control means for printing apparatus, in particular for offset printing machines

ABSTRACT

A control shaft for an offset printing machine, provided with cams, levers and the like for controlling the various operations during a printing cycle, is provided with a knob for manual rotation and with a ratchet wheel for step-by-step rotation by a pawl oscillated cyclically by a cam rotatable with one of the cylinders of the printing machine. The ratchet wheel has a number of switching ratchet teeth corresponding to the number of switching stages of the printing machine. Certain of the ratchet teeth have a sawtooth shape whereby, when engaged by the pawl, the ratchet wheel is advanced by one step. Other teeth of the ratchet wheel have a special shape including a protuberance on the flank leading to the radial portion of the tooth normally engaged by the pawl. These protuberances cause the pawl to travel out of its normal path of movement when engaged with one of these special form teeth. A spring biased locking disc is arranged adjacent the pawl and is axially displaceable by energization of an electromagnet. The locking disc is biased to engage beneath the ratchet pawl, when the pawl is displaced out of its normal path of movement due to engagement with a tooth of special shape, and the locking disc thereby prevents engagement of the pawl with the next succeeding tooth of the ratchet wheel even though the pawl continues to be oscillated. When the electromagnet is energized, the locking disc is axially displaced from its pawl blocking position, against the bias of a spring, allowing the pawl to again cooperate in a normal manner with the teeth of the ratchet wheel.

United States Patent [191 Raible June 26, 1973 CONTROL MEANS FORPRINTING APPARATUS, IN PARTICULAR FOR OFFSET PRINTING MACHINES [75]Inventor: Hermann Raible, St. George n, Black Forest, Germany [73]Assignee: Mathias Bauerle Gmbll, Georgen,

Black Forest, Germany [22] Filed: Sept. 1, 1971 [21] Appl. No.: 176,930

[30] Foreign Application Priority Data Primary Examiner-Herman J.Hohauser Att0meyJohn J. McGlew and Alfred E. Page [57] ABSTRACT Acontrol shaft for an offset printing machine, provided with cams, leversand the like for controlling the various operations during a printingcycle, is provided with a knob for manual rotation and with a ratchetwheel for step-by-step rotation by a pawl oscillated cyclically by a camrotatable with one of the cylinders of the printing machine. The ratchetwheel has a number of switching ratchet teeth corresponding to thenumber of switching stages of the printing machine. Certain of theratchet teeth have a sawtooth shape whereby, when engaged by the pawl,the ratchet wheel is advanced by one step; Other teeth of the ratchetwheel have a special shape including a protuberance on the flank leadingto the radial portion of the tooth normally engaged by the pawl. Theseprotuberances cause the pawl to travel out of its normal path ofmovement when engaged with one of these special form teeth. A springbiased locking disc is arranged adjacent the pawl and is axiallydisplaceable by energization of an electromagnet. The locking disc isbiased to engage beneath the ratchet pawl, when the pawl is displacedout of its normal path of movement due to engagement with a tooth ofspecial shape, and

the locking disc thereby prevents engagement of the pawl with the nextsucceeding tooth of the ratchet wheel even though the pawl continues tobe oscillated. When the electromagnet is energized, the locking disc isaxially displaced from its pawl blocking position, against the bias of aspring, allowing the pawl to again cooperate in a normal manner with theteeth of the ratchet wheel.

lllClaims, 9 Drawing Figures PATENTED JUN26 I975 SHEET R [If 5 CONTROLMEANS FOR PRINTING APPARATUS, IN PARTICULAR FOR OFFSET PRINTING MACHINESBACKGROUND OF THE INVENTION 1. Field of the Invention The inventiondeals with printing machine controls having a control shaft withelements in cooperation with the latter to influence the shaft forperforming numerous desirable operative steps.

2. Description of the Prior Art In known machines, it was not onlynecessary to maintain a certain chronological order in starting andstopping various machine operations, but certain time intervals werealso required in starting and stopping certain machine operations, sothat printing could be performed after the first sheet has beenintroduced and the machine was then made ready for a new printingoperation after it has been previously stopped. In a known printingmachine, the machine control shaft was equipped with a great number ofswitching stages which effectuate individually starting and stopping ofmachine operations: e.g.

I Off II Motor on Washing Device on (only at reverse run);

III inking device switched on;

IV Moistening Device in operation;

V Etching Device becomes effective;

VI Inking Cloth Roller applied to sheet roller;

VII Rubber Cloth Roller applied to sheet roller;

VIII Paper feed or supply switched on for printing.

In a known printing machine, a control motor is provided for actuatingthe respective switching devices, which motor, after it has been startedmanually, drives several trip cams effecting the switching operations.The positions of the individual active flanks of these trip cams areadjusted to each other corresponding to a predetermined switching order.The purpose of this arrangement is to. make the switching time for thesequential startingand stopping movements independent of the manualswitching. By pushing a key, the control motor is started through aholding relay and a program card, which is conformed to its programmarkings and to the respective selected printing program, moves aheadalways one step forward. The program card is advanced by means of aratchet mechanism which receives its impulses from the impulsetransmitter actuated during the revolutions of the impression roll. Themain disadvantage of this known control device is that it increasessubstantially the cost of the printing machine due to the necessaryaccessories and loss of time. Besides this, the program card providedfor the control results in a cumbersome operation and a special controlmotor must be provided for carrying out the control itself. Though theforward switching of the program card is effected by means of a ratchetmechanism and of a corresponding impulse transmitter in accordance withthe rhythm of the machine cycles, these accessories do not ensure thestart and stop of individual machine operations in synchronism withrespective machine cycles.

In another known control device used for offset printing machines, thecontrol shaft is adjustable between a starting position, at least oneintermediate operating position and a last operating position, timedelay relays being provided which can be adjusted to different runningtimes, by means of which the stepping mechanism which effects thestepping of the control shaft from one position to the other, can becontrolled corresponding to the desired operating time of the unitsactuated by the control shaft. The purpose of this known control deviceis to effectuate a variation in starting and stopping time and in theduration of the operations within certain limits by means of a singlecontrol shaft which controls the operation or, if desired, by hand.However, this control device, too, is very expensive, complicated tooperate and is highly susceptible to trouble, disturbancesandinterruptions.

SUMMARY OF THE INVENTION The object of the present invention is toprovide simple and inexpensive means, easy and reliable to operate whichresult in a highly economical control system which permits to regulatethe switching sequence of the machine control shaft both in dependenceon the control elements inherent in the machine and persuant to a presetprinting program, and to switch individual and- /or several sections ofthe switching program by manual operation of an electric switchingsystem by means of a ratchet mechanism, so that the end of eachindividual section of the switching program or system will be alwayspredetermined.

The invention is primarily characterized in that the ratchet mechanismpossesses, for cooperation with any stepwise switching of the controlshaft certain means, e.g., a ratchet wheel mechanism with a number ofpreshaped ratchet teeth the conformation of which corresponds to theindividual switching stages. A locking member which can be disengagedfrom the respective form of the ratchet teeth after their respectiveperformance, is actuatable by a control magnet (electromagnet) accordingto the machine cycles via an oscillatable feed pawl or control lever.Consequently the particular control means are accommodated in and formparts of the ratchet mechanism itself, so that there is positivelyachieved a synchronism between the machine cycles and the switchingfunctions of the control shaft. Furthermore, additional program controlelements, which could influence the cost of the machine can becompletely eliminated. The surveillance and operation of the printingmachine will be greatly simplified.

The special advantage derived from the solution of this problem is thatthe switching program of the control shaft is not tied up, as in knownmachines, with additional separate control devices, but includes aratchet mechanism which ensures, on one hand a positive synchronismbetween the machine cycles and the switching operations of the controlshaft, and eliminates, on the other hand, additional program controlelements which otherwise complicate the operation of and contribute tothe increase of the cost of themachine. The operation is alsosubstantially simplified, individual program sections being switched atany time corresponding to given requirements without substantiallychanging the total program of the machine.

According to a further development of the invention, an electromagnet orlike element actuates the locking element of the pawl, severalindependent control circuits with electric switches being providedtherefor, of which one circuit is controlled by hand, another circuit bya sheet counter, and still a further circuit by the rising table of themachine. Additionally still another circuit becomes effective by arevolution counter of the washing device of the machine.

It is one of the important objects of the present invention to providemeans leading to many other advantages according to which individualprogram, sections of the entire switching program can be assigned in asimple manner to certain machine operations and be controlled by thelatter, while other machine operations can effect the entire course ofthe switching program, while in addition, the course of individualprogram sections can be controlled by hand.

Another essential feature of the invention is that the specially formedratchet teeth of the ratchet wheel are shaped and specifically providedon the reverse side of the teeth with protuberances and the like, whileother ratchet teeth are saw-shaped, the cooperable pawl having a lockingpart laterally overlying its ratchet teeth which cooperate with thelocking element.

In other words, the present invention makes use of and contemplatesspecially-shaped ratchet teeth to represent the program control elementsproper. Thus, the ratchet wheel or like element comprises the switchingprogram. The program control proper is effected in this manner strictlyby mechanical means and is therefore very reliable and not susceptibleto ineffectiveness or disturbances.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated preferred embodiments'of theinvention.

Other advantageous features of the invention will result from thefollowing description of a preferred embodiment of the invention inconnection with the draw- Ings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view ofessential parts of a control device embodying the'invention as appliedto an offset printing machine in which the control shaft is turned byhand for starting individual machine operations and in which theindividual operations are stopped by means of a ratchet mechanism;

FIG. 2 shows in perspective the control shaft and the essential parts ofsaid ratchet mechanism;

FIG. 3 is a side elevation view of some of the individual parts of theratchet mechanism;

FIG. 3a depicts the ratchet wheel of the ratchet mechanism as seen inside view;

FIG. 4 illustrates the arrangement of the parts of FIG. 3 in frontelevation view, partly in section;

FIG. 5 is a side elevation view of the arrangement of individual partsof the counter mechanism employable with the washing device;

FIG. 6 is a side elevation view of the adjusting means for therevolution counter mechanism;

FIG. 7 is a side elevation view of the control elements of the counter;and

FIG. 8 is a circuit diagram of the various control circuits foroperating the control magnet.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring more and ingreater detail to the drawings,

there is disclosed a reset ratchet mechanism of the control shaft ll ofan offset printing machine. On control shaft 1 there are arrangedindividual cams 1 to 8, which effectuate the starting and stopping ofvarious operations in a predetermined order. Cam 2 actuates the mainswitch of the machine motor, cam 3 controls the paper feed, cam 4 checksthe application and removal, respectively, of the sheet or foil cylinderto and from the rubber cloth cylinder, control lever 5 controls theetching device and earns 6 and 7 operate the inking-and washing device,e.g. the inking roller. Double cam device 8 becomes operative onlyduring the reward or reverse movement of control shaft 1 and sets thewashing device in motion in stage II in which all other operations ofthe machine have already been stopped or deenergized (FIG. 3a) and onlythe main motor remains in action. Double cam device 8, which consists oftwo cams 9 and 10, acts on the angle lever 11 and on its feeler roller12, which lever 11 is pivotally mounted on a stationary pivot 13 and isunder the action of a spring 14 which exerts a torque in clockwisedirection on angle lever 11 (FIG. 1). On the left hand end of controlshaft 1 (FIG. 2) there is ar-ranged a handle 15. Rigidly connected withcam drive or disk 10 by a bushing assembly 16 is a notched star wheel 17which is engaged by a stop roller 18 carried by stop lever 19, which inturn is pivotally mounted on a stationary pin20 and which is under theaction of a tension spring pulling it radially toward notched roller 17.On stop lever 19 there is pivotally mounted relative to the latter on apivot 21 a pawl 22 which cooperates with a locking disk 23 whosefunction will be described further below. A pin 24 on stop lever 19, onwhich roller 18 is rotatably mounted, engages a bore 25 of pawl 22 whosediameter is substantially greater than the diameter of pin 24. In thismanner the pivotal movement of pawl 22 is limited by pin 24 in bothpivotal directions. A tension spring 26 always pulls pawl 22 in downwarddirection. Rigidly connected with notched star wheel 17 and thus withcontrol shaft 1 is a ratchet wheel 27 which is shown in FIG. 3a in sideview. This ratchet wheel 27 has eight ratchet teeth I VIII, which areassociated with or coordinated to the individual switching positions ofcontrol shaft 1. Ratchet tooth I corresponds to the position Off,ratchet tooth II to the position motor on, or to the operation washingin rearward operation, ratchet tooth III to the start of the inkingmechanism, ratchet IV to the start of the washing device, ratchet toothV to the start of the etching operation, ratchet tooth VI to theoperation for application of rubber cloth cylinder to the impressionsheet cylinder and ratchet tooth VIII to the operation of paper infeed.

As it can be gathered particularly from FIG. 3a, the rear parts of theratchet teeth l,Il,V and VI are provided each with a protuberance whilethe ratchet teeth lll,lV, VII and VIII have a normal flat rear saw toothshape. This means that ratchet wheel 27 constitutes or makes up aprogram according to which the individual machine operations have beendeveloped and take place as will hereinafter be explained.

Associated with ratchet wheel 27 is a pawl 29 which is set into anoscillating motion by a cam disk 33 through intermediate levers 30 and31 (FIG. 1) connected with each other by a link 32. Cam disk 33 isarranged on shaft 34 of the rubber cloth cylinder of the printingmachine. Pawl 29 is pivotally mounted on a pivot 35 of lever 30 and isguided in a chordal slot 36 of a bush 38 pivotally mounted in theproximity of ratchet 27 on a pivot 37. In bush 38 there is secured,parallel to the longitudinal direction of the pawl 29, a spring rod 39,(FIG. 3) which loosely engages a stirrup 40 secured on pawl 29. The pawl29 consists of two parts, namely a switching part 41 which has a ratchettooth 42, and a locking part 43 covering the ratchet tooth 42 laterallyand cooperating with the locking disk 23.

Disk 23 is mounted for axial movement on the outer end 44 of controlshaft 1 and is provided with a bush 45 which has an annular groove 46.The annular groove 46 is engaged by a pin or pivot 47 of a rocker arm 48whose other end is connected to an armature 49 of a control segment 50.Rocker 48 is mounted on a stationary journal for pivotal movement in aplane parallel to the axial direction of control shaft 1 and is underthe action of a tension spring 51 which urges stop disk 23 against theratchet wheel 27 when the control magnet 50 is not energized.

Connected to bush 38, which is provided on its circumference the chordalslot 36 for guiding the pawl 29, is a lever 52 which protrudes with itsfree end into the path of a pin 53 which is arranged in ratchet wheel 27and also protrudes through an arcuate slot 54 in looking disk 23.Besides this, lever 52 is under the action of a tension spring 55 whichurges it toward the axis of control shaft 1 and exerts on it a torque incounterclockwise direction.

The electric control of control magnet 50 takes place according to thediagram of FIG. 8. Several independent circuits in parallel are assignedto control magnet 50. In one control circuit there is arranged a makecontact switch S7 controlled by a sheet counter 56, which is shown onlyschematically and which is in series with a reset contact switch 58which is actuated by a retaining pawl 59 of a counting wheel 60 by meansof angle lever 11. As mentioned above, angle lever 11 is controlled bydouble cam 8, comprising cams 9 and 10, respectively, on controlshaft 1. In a parallel circuit there is arranged a hand-operated pushbutton switch 61 and in parallel thereto a rising table switch 62 whichis closed briefly when the rising table (not represented) drops, thatis, when the paper on the rising table is used up. A third controlcircuit of control magnet 50 contains the make contact switch 63 whichis closed by counting wheel 60 of the revolution counter 64 of thewashing device when the required number of washing revolutions has runoff.

The reset of control shaft-1 can thus be effected by the sheet counter56 or manually by push button switch 61 or by the rising table by meansof table switch 62 and additionally by switch 63 actuated by therevolution counter 64. The number of operational stops that must becarried out during the closing of the individual control circuitsdescribed above depends, during the actuation of the switches 57, 61 and62, exclusively on the program incorporated in and directed to theratchet teeth Ito VIII of ratchet wheel 27. Only by push button switch61 is it also possible to suppress this program and to return directlyinto position I from position VIII by continued pressure on push buttonswitch 61.

The above mentioned counting wheel 60 of counter 64 is rotatably mountedon a stationary pivot 65 and has a switching pin 66 in whose path isarranged the make contact switch 63. The starting pivot of the countingposition of counting wheel 60 can be preadjusted by an adjustable wheelby means of pinion 67 which engages a toothed segment 69 which ispivotally mounted on pivot 68. The toothed segment 69 is in operativeconnection with a pinion 76 of adjusting wheel 70, by means of a pin 71which engages an oblong slot 72 of a joint bar 73, which is operativelyconnected with toothed segment 74 by means of a pin 75. The toothedsegment 74 is pivotally mounted on a stationary journal 77 (see FIGS. 5to 7).

The toothed segment 69 is also under the action of a tension spring 78which exerts a torque in clockwise direction (FIG. 6).

Counting wheel 60 is operated by finger 80 of a pawl 79 which isengaged, by means of an oblong slot 81 with a pin 82 reaching into thelatter via retaining pawl 59, for displacement in the direction of theoscillatory movement of pawl 79 and which is under the action of returnspring 83 (FIG. 5).

Pawl 79 with its operable finger 80 is actuated in the operatingposition as shown in FIG. 5 by an element 84 of pawl 29 in whose pathfinger 80 arrives when retaining pawl 79 comes into engagement with theteeth of counting wheel 60. This is the case when the feeler roll 12 ofkey lever 11 drops during the rearward switching of control shaft 1 ontothe lateral curve 85 of cam 9 arranged on control shaft 1 and retainingpawl 59 releases the tension of spring 83.

Depending on the position of counting wheel 60 and its pin 66 preset bythe adjusting wheel 70, a certain number of machine cycles takes placeuntil pin 66 closes the make contact switch 63 and thus energizescontrol magnet 50, which then pulls locking disk 23 over rocker 48 outof the range of pawl 29 so that ratchet tooth 42 engages ratchet wheel27 and control shaft 1 returns to its off position.

As soon as control shaft 1 reaches its off position, the feeler roll 12of key lever 11 is again on the large radius of cam 9, as seen in FIG.7, so that retaining pawl 59 is again disengaged and closes the restcontact switch 58 by means of pin 86. The rest contact switch 58 and itsabove described control mechanism is necessary so that, when the machineis stopped by sheet counter 56, the revolution counter 64 of the washingdevice can become operative and the make contact switch 57 actuated bysheet counter 57 is made inoperative for the duration of the washingprocess.

The revolution counter 64 for the washing device, which is started bymeans of lever 11, becomes effective only in position II of the controlshaft 1, namely, only when this position of control shaft 1 is startedin reverse drive direction. This condition is met by double cam 8 whichincludes the two single cams 9 and 10. In the forward direction ofrotation of the cam corresponding to arrow 87 (FIG. 7) the feeler roll12 of lever l 1 can not follow the dropping curve 85 of cam 9 since thelatter is covered by cam 10 which is rotatable relative to cam 9 by Onlyduring the rotation of control shaft 1 in reverse does the feeler roll12 of lever 11 fall into a notch 88 formed between the two cams 9, 10and displaces then cam 10 relative to cam 9, while it follows thedropping flank 85 and performs the above described operations.

The method of operation of the ratchet mechanism described above is asfollows: Assuming that all machine operations are effective and thatratchet wheel 27, arrives in the position of ratchet tooth I as seen inFIG. 3a, upon corresponding manual rotation of handle 15, then lockingdisk 23 keeps pawl 29 out of engagement with ratchet wheel 27, so thatno switching operation takes place with respect to control shaft ll,despite the fact that pawl 29 constantly oscillates in the rhythm of theindividual machine cycle. While in position I of control shaft ll, pin53 of ratchet wheel 27 keeps lever 52, pivotal on bearing pin 37, in aposition in which spring rod 39 keeps pawl 29 out of engagement withratchet teeth I to VIII of ratchet wheel 27, pin 53 being now turned sofar with ratchet wheel 27, due to the rotation of control shaft I inforward direction, that it releases lever 52, which is under the actionof tension spring 55, so that the latter turns lever 52 incounterclockwise direction and spring rod 39 presses pawl 29 againstratchet wheel 27 and against locking disk 23 (FIG. 4). As long ascontrol magnet 50 is not energized, locking disk 23 is in the positionof FIG. 4, in which it keeps pawl 29 out of engagement with ratchetwheel 27. Pawl 29 thus performs only idle strokes in this position oflocking disk 23 and does not influence counting wheel 69 (FIGS. 1 and5-7) of the revolution counter 64. The reverse movement of control shaftl by pawl 29 and ratchet 27 can be determined by three different causes.

Assuming that the paper supply on the so-called rising table of theprinting machine is prematurely used up, the rising table switch 62 isbriefly closed by the rising table when it has reached a certain level.Control magnet 50 is energized and its armature 49 pulls locking disk 23over rocker arm 48 away from ratchet wheel 27 into the position of FIG.2. Pawl 29 is thus released and is brought by the action of spring rod39 into engagement with ratchet tooth VIII to turn control shaft back byone tooth division of ratchet wheel 27 as indicated by the direction ofarrow 89 (FIG. 3). Though control magnet 50 has in the meantime becomedeenergized again, because the rising table switch 62 was opened again,locking disk 23 can at first not return into its locking position (FIG.4) because it abuts laterally against locking part 43 of pawl 29. Duringthe reverse stroke of pawl 29 the latter is not deflectedradially by thesawtooth form of the ratchet teeth VIII and VII of ratchet wheel 27 tosuch an extent that locking disk 23 could move again into the lockingposition, so that ratchet tooth VII is also stepped up during the nextstroke. During the following reverse stroke of pawl 29, ratchet tooth 42of pawl 29 slides over the protuberance 28 of ratchet tooth VI and isdeflected radially by pawl 29 so far that locking disk 23 is urged againinto the locking position represented in FIG. 4 and this keeps pawl 29out of its engagement position. After turning control shaft I back fromposition VIII into position VI, the action of the ratchet mechanism isthus automatically stopped. In position VI of control shaft 1 the papersupply is shut off and the rubber cloth roller is removed from thesheeting roller so that overinking of the rubber cloth roller isprevented, while a new stack of paper sheet is placed on the risingtable. Subsequently control shaft 1 can be turned again by hand intoposition VIII in which the printing is continued.

The same operational sequence takes place when push button switch 61 isactuated briefly by hand. The operator or supervisor has thus thepossibility of stopping the printing process at any time in a simplemanner without paying special attention to the printing operation inorder to check, for example, the printing result.

Since switching tooth V is also provided with protuberance 28, it ispossible, if necessary by again operating briefly push button switch611, to turn control shaft 1 back from position VI into position V inwhich pawl 29 is then again brought automatically out of engagement.

Since the two ratchet teeth IV and III are not provided with aprotuberance 28, control shaft ll moves directly from position V intoposition II if push button switch 611 is pressed again briefly, in whichit then remains until the revolution counter 64 closes the make contactswitch 63 and energizes again control magnet 59 in order to bring againpawl 29 in engagement with ratchet wheel 27 for the last steppingmovement from position II into poisition I.

Naturally, by pressing constantly push button switch 61 and energizingcontrol magnet 50 for a correspondingly long time the lock disk 23 canbe kept out of range of pawl 29 so long until the control shaft hasmoved from position VIII directly into position I. This emergency stopmust also be possible, for example, when trouble is detected in theoperation of the ma chine.

Due to the above described hand-controlled reverse movement of controlshaft )1 from position VIII into position V, in which, in addition tothe machine motor, the inkingand the washing device, the etching deviceis also started, it is possible for example, to also check the operationof the etching device. I

The step-to-step shut-off of the machine by means of the paper sheetcounter 56 occurs in a manner that upon reaching a pre-arranged numberof the counter 56 the make-contact switch S7 is closed to the extent,until the operation shaft I has arrived at the position IV in which theengagement of the key lever Ill with the bottom of the control cam 9opens the rest contact switch 58 (FIGS. ll, 5, 7 and 8) and the controlmagnet is shut off. As hereinabove mentioned the revolution countermechanism 6 3 is then actuated which upon reaching the predeterminednumber of sheets closes the make-contact switch 63 and the reversal ofrotation of the control shaft from position II to the operative positionI is effectuated, in which the machine is completely stopped.

Even if only the programmed reverse-step operation is mentioned in theforegoing disclosure this should not be construed that the forward stepcontrol of the operating shaft from position I to the position VIII cannot be effected in a similar manner. To this end it is only necessary touse a second ratchet mechanism which acts in the opposite direction ofrotation and which is likewise equipped with ratchet teeth like theratchet wheel 27. In order to provide for certain stepping halts orbreaks between certain stepping positions of control shaft ll during theforward operation, similar counters can be used in the same manner, andthe revolution counter 6% described above, with corresponding electriccontrol switches. The control of the ratchet mechanism itself for theforward stepping of control shaft I can be effected in a simple mannerwith an auxiliary control magnet (not shown).

In order to prevent locking disk 23! from falling back into its lockingposition when the control magnet 50 is only briefly energized, beforepawl 29 is in engagement with ratchet wheel27, the pawl 22 provided onstop lever 19 which is removed from the range of motion of locking disk23 whenever the feeler roll 18 of key lever 19 slides over a tooth ofnotched star wheel 17 which drops down immediately, however, whenlocking disk 23 is removed from ratchet wheel 27, and prevents lockingdisk 23 from reverse movement.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. In a control device for printing machines, particularly offsetprinting machines, having a control shaft provided with controlelements, such as cams, for the individual machine operations, thecontrol shaft being stepwise displaceable by hand or by a ratchetmechanism, controlled by an electromagnet, into different positions tostart and stop the individual operations before, during and afterprinting: the improvement comprising, in combination, said ratchetmechanism including a ratchet wheel secured to said control shaft andhaving a number or ratchet teeth corresponding to the number ofindividual steps included in an operating cycle of the printing machine;a pawl mechanically oscillated in the cycle of the printing machine andengageable with said teeth to step said control shaft; each tooth havingan operating edge engageable by said pawl to step the ratchet wheel anda back edge extending from its operating edge and over which the pawlmoves to engage the operating edge; certain of said teeth having aspecial configuration of the back edge which, when engaged by said pawl,displaces said pawl out of its normal path of oscillation; a lockingelement engageable with said oscillating pawl when said pawl is sodisplaced out of its normal path of oscillation, to retain said pawl outof its normal path of oscillation to halt further stepping of saidcontrol shaft by said oscillating pawl; and means operable, responsiveto energization of said electromagnet, to disengage said locking elementfrom said pawl for return of said pawl to its normal path of oscillationto further step said control shaft.

2. In a control device, the improvement claimed in claim 1, including aplurality of energizing circuits, including electric switches,independently selectively operable to connect said electromagnet to asource of electric potential; one circuit including a normally openedmanually closed switch, a second circuit including a normally openswitch closed by a sheet counter included in said printing mechanism, athird circuit including a normally open switch closed by a rising tableincluded in said printing mechanism, and a fourth circuit including anormally open switch closed by a revolution counter included in thestepping mechanism of said printing machine.

3. In a control device, the improvement claimed in claim 1, in which thespecial configuration of the back edge of said certain ratchet teethcomprises respective protuberances on the back edges of said certainratchet teeth; the other ratchet teeth having a sawtooth shape; saidpawl including a ratchet tooth engageable with the operating edges ofsaid ratchet teeth on said ratchet wheel, and including a locking partjuxtaposed with the ratchet tooth of said pawl and cooperable with saidlocking element.

4. In a control device, the improvement claimed in claim 3, in whichsaid locking element is a circular disc; said ratchet wheel beingsecured to a shaft and said circular disc being mounted on said shaftfor axial displacement relative to said locking part of said pawl; and apivotally mounted rocker arm connecting said circular disc to saidelectromagnet for axial displacement of said circular disc.

5. In a control device, the improvement claimed in claim 1, including aspring operatively associated with said pawl and biasing said pawlrelative to said ratchet wheel; the operative connection of said springbeing reversible relative to said ratchet wheel.

6. In a control device, the improvement claimed in claim 5, in whichsaid spring is a leaf spring having one end secured to a pivotallymounted lever and its opposite end operatively associated with saidpawl; a protuberance on said ratchet wheel engageable with saidpivotally mounted lever to swing the same in one direction; and atension spring connected to said pivotally mounted lever and biasing thesame to swing in the opposite direction.

7. In a control device, the improvement claimed in claim 4, including ablocking pawl pivoted to swing radially relative to the shaft of saidratchet wheel in the range of axial displacement of said circular disc;a pivoted stop lever pivotally mounting said blocking pawl and engagedwith a star wheel fixed to rotate with said ratchet wheel; means on saidlocking lever engageable with play with said blocking pawl; saidblocking pawl, responsive to axial displacement of said circular discdue to energization of said electromagnet, dropping behind said circulardisc to prevent return of said circular disc to a position operable tomove said oscillating pawl out of its normal path of oscillation; saidblocking pawl being retracted out of blocking relation with saidcircular disc responsive to swinging of said locking lever by said starwheel.

8. In a control device, the improvement claimed in claim 2, including amake-contact switch and a restcontact switch connected in series in oneof the energizing circuits of said electromagnet; said make-contactswitch being actuated by a counting wheel moving stepwise in the rhythmof the printing machine; said restcontact switch being actuated by alever controlled by said control shaft.

9. In a control device, the improvement claimed in claim 8, in whichsaid last-named lever is constituted by a retaining pawl for a countingwheel of a revolution counter of a washing device included in theprinting machine.

10. In a control device, the improvement claimed in claim 9, including aslide having a ratchet tooth mounted on said retaining pawl fortangential displacement toward said counting wheel; and a trip cam onsaid oscillating pawl actuating said slide when said retaining pawl isin engagement with said counting wheel. 5 i 1 4

1. In a control device for printing machines, particularly offsetprinting machines, having a control shaft provided with controlelements, such as cams, for the individual machine operations, thecontrol shaft being stepwise displaceable by hand or by a ratchetmechanism, controlled by an electromagnet, into different positions tostart and stop the individual operations before, during and afterprinting: the improvement comprising, in combination, said ratchetmechanism including a ratchet wheel secured to said control shaft andhaving a number or ratchet teeth corresponding to the number ofindividual steps included in an operating cycle of the printing machine;a pawl mechanically oscillated in the cycle of the printing machine andengageable with said teeth to step said control shaft; each tooth havingan operating edge engageable by said pawl to step the ratchet wheel anda back edge extending from its operating edge and over which the pawlmoves to engage the operating edge; certain of said teeth having aspecial configuration of the back edge which, when engaged by said pawl,displaces said pawl out of its normal path of oscillation; a lockingelement engageable with said oscillating pawl when said pawl is sodisplaced out of its normal path of oscillation, to retain said pawl outof its normal path of oscillation to halt further stepping of saidcontrol shaft by said oscillating pawl; and means operable, responsiveto energization of said electromagnet, to disengage said locking elementfrom said pawl for return of said pawl to its normal path of oscillationto further step said control shaft.
 2. In a control device, theimprovement claimed in claim 1, including a plurality of energizingcircuits, including electric switChes, independently selectivelyoperable to connect said electromagnet to a source of electricpotential; one circuit including a normally opened manually closedswitch, a second circuit including a normally open switch closed by asheet counter included in said printing mechanism, a third circuitincluding a normally open switch closed by a rising table included insaid printing mechanism, and a fourth circuit including a normally openswitch closed by a revolution counter included in the stepping mechanismof said printing machine.
 3. In a control device, the improvementclaimed in claim 1, in which the special configuration of the back edgeof said certain ratchet teeth comprises respective protuberances on theback edges of said certain ratchet teeth; the other ratchet teeth havinga sawtooth shape; said pawl including a ratchet tooth engageable withthe operating edges of said ratchet teeth on said ratchet wheel, andincluding a locking part juxtaposed with the ratchet tooth of said pawland cooperable with said locking element.
 4. In a control device, theimprovement claimed in claim 3, in which said locking element is acircular disc; said ratchet wheel being secured to a shaft and saidcircular disc being mounted on said shaft for axial displacementrelative to said locking part of said pawl; and a pivotally mountedrocker arm connecting said circular disc to said electromagnet for axialdisplacement of said circular disc.
 5. In a control device, theimprovement claimed in claim 1, including a spring operativelyassociated with said pawl and biasing said pawl relative to said ratchetwheel; the operative connection of said spring being reversible relativeto said ratchet wheel.
 6. In a control device, the improvement claimedin claim 5, in which said spring is a leaf spring having one end securedto a pivotally mounted lever and its opposite end operatively associatedwith said pawl; a protuberance on said ratchet wheel engageable withsaid pivotally mounted lever to swing the same in one direction; and atension spring connected to said pivotally mounted lever and biasing thesame to swing in the opposite direction.
 7. In a control device, theimprovement claimed in claim 4, including a blocking pawl pivoted toswing radially relative to the shaft of said ratchet wheel in the rangeof axial displacement of said circular disc; a pivoted stop leverpivotally mounting said blocking pawl and engaged with a star wheelfixed to rotate with said ratchet wheel; means on said locking leverengageable with play with said blocking pawl; said blocking pawl,responsive to axial displacement of said circular disc due toenergization of said electromagnet, dropping behind said circular discto prevent return of said circular disc to a position operable to movesaid oscillating pawl out of its normal path of oscillation; saidblocking pawl being retracted out of blocking relation with saidcircular disc responsive to swinging of said locking lever by said starwheel.
 8. In a control device, the improvement claimed in claim 2,including a make-contact switch and a rest-contact switch connected inseries in one of the energizing circuits of said electromagnet; saidmake-contact switch being actuated by a counting wheel moving stepwisein the rhythm of the printing machine; said rest-contact switch beingactuated by a lever controlled by said control shaft.
 9. In a controldevice, the improvement claimed in claim 8, in which said last-namedlever is constituted by a retaining pawl for a counting wheel of arevolution counter of a washing device included in the printing machine.10. In a control device, the improvement claimed in claim 9, including aslide having a ratchet tooth mounted on said retaining pawl fortangential displacement toward said counting wheel; and a trip cam onsaid oscillating pawl actuating said slide when said retaining pawl isin engagement with said counting wheel.